Combined power steering and shimmy dampening



w. H. CLARK Get. 6, 1953 COMBINED POWER STEERING AND SHIMMY DAMPENINGFiled Sept. 8, 1950 2 Sheets-Sheetl 1 new.

W. H. CLARK COMBINED POWER STE Filed Sept. 8, 1950 Oct. 6, 1953 ERINGAND SHIMMY DAMPENING 2 Sheets-Sheet 2 lNvENToR Men/v hf CMM.

/l/'s ATTORNEY Patented Oct. 6, 1953 COMBINED POWER STEERING ANDSHIIVIMY DAMPENING Warren H. Clark, Glendale, Calif., assigner to UnitedAircraft Products, Inc., Dayton, Ohio, a corporation of Ohio ApplicationSeptember 8, 1950, Serial No. 183,862

4 Claims.

This invention relates to power steering and shimmy dampener apparatus,particularly as combined in a unitary structure.

An object of the invention is to condition the apparatus for alternativeuse as ashimmy damp- 5 to the pressure chamber it and by a passage eneror power steerer simply by adjustment of t2 to the chamber 39. Thegroove 34 is cona single control. nected by a passage i3 to a source 41%of hy- Another object of the invention is to present draulic pressurefluid, a branch 45 of the passage a hydraulic circuit for combined powersteering d3 communicating with the chamber 39. The and shimmy dampening,utilizing two slide valves m groove 3e is connected to the chamber 39 byfor control thereof, one of said valves function a passage lle. ing as acontrol element to shift the operational Also connected to the chamber39 is a pascharacter of the circuit from power steering to sage iiicommunicating with the pressure cham- Shfljflytempkehihtg and ViCeVersa. 15 ber Il. The passage 4'! and branch passage 45 ur er o jec ofthe invention is to accomopen into the opposite ends of the chamber 39.Dlish power Steering thIOugh apparatus func- The several passages 3l, i2and et communicate tioning as a servoemechanism with mechanical with theside of the chamber in longitudinally IOl/-up-b t d L 1 spaced relationto one another.

er O jee S en Struulal detai S of the iIl- Mounted for limited axialmotion in the chamv ention will appear from the following descrp- 20 ber39 is a slide valve 48 presenting a central tion when read in clnnectionwith the accombore is and longitudinally spacedlacialt 1rort panyingdrawings, W ereln: 5i and 52, the bore i9 opening into e ef an Fis. 1 isa View, in part diagrammatic, 0f the end of chamber se. A spring 53urges the valve tmparatlclls as Set for Shlmmy dampenins Opera- 25 is toa seat in the right hand end of the chamber lon; an o @Q f Fig- 2 iS aVieW Similar t0 Fig- 1, ShOWiIlg the The reservoir Se contains a piston54, bearing apparatus as set for power steering. the thrust of a spring55, and functions as a Referring t0 the Cirawlngee rotatable DOWeIhydraulic accumulator. A passage 5t, contain- Output Shaft i0 1S formedWlth geel" teeth deing a check valve 5l, connects the reservoir orflhilrlgl a DihOh itl Ileshh With a Tk i- The 3o accumulator to thehydraulic fluid Isource rac 2 is a par o a DiS 011 aSSem YCompristhrough passage 153. As influenced by t e ac- Ilg intelCOhIleCtedpiStOhS i3 and i4 TeCiDYOCabie cumulator, therefore, the pressure in thesystem in a Cyllnder I5. The plstons I 3 and It, together is thatestablished by the resistance of check with the ends of the cylinder I5,denne respective Valve si, Pressure Chambers i3 and |7- 35 The passagei3 has therein an oppositely fac- The pinion Il is located adjacent theouter ing (with respect to valve 5l) check valve et, sind of the shaftID. tThe oOppOSifg l illhel endas well as a pump 5B and a two-way valve6i. t eleOf iS formed Wi h a @Ye 0 TeCeVe a The pump 59 may for purposesof description be COI1t101 input Shaft. i9 arranged fol relatle 1'0"considered a continuously operating pump while giaitailg.ileailvgouprixsi 2? lt Sslycfzti lign gig l0 the valve ti is manually olothetrwse settable rtg a rst position in which t e ou put of pumpconstruction and arrangement being such that hr u h b ass 6 nd to aSecrelative rotary motion between the shafts It and jsnlrg tin vicr'tgeppumpz utput is ad: I9 results 1n an axial movement of the-shaft I9.mtted to passage 3 While Continuing to have The lnner end of the shafti9 1s constructed as 45 access to the by-pass 62. A pressure reliefvalve a sl1de valve 23 having annular lianges 24 and n 63 1n the by-pass32 pein'uts flow through the 25 and a bore 26 opening at 1ts one endinto the l d t d h. h re re bottom of bore is. At its opposite end thebore *3y-Pass OP Y at e P re e emma 1g 1 Ss 26 communicates throughradial ports 27 with value, which value 1s higher than the pressure thebore I8 at a point outwardly of or above the 50 velue et Whlch CheckValve 53 Open I h flange 24 The passages iii and el, communlcatmg withThe slide valve 23 controls a series of radial lOYeSSUlle Chambers i@and i7 Contain dentic ports 28, Ei, 353 and 3i in the shaft i whichrestrictor valves et and E5. In structural detail, ports register withrespective annular grooves 32, and referring to Valve 54, each 0f theseValves 33, 34 and 35. Communicating with the groove 55 comprises atubular, plunger type valve S5 urged 32 is a passage 3S leading to apassage 31, the latter being connected at its one end to a uid reservoir38 and at its other end to a chamber 39. The groove 33 is connected by apassage 4l `entire output of .pump 59.

3 by a spring B1 to a seat in a chamber 68, the chamber 68 beinginterposed in the passage 4|. A small opening 69 in the end of valve 6B,and radial ports '|I therein establish continuous communication throughthe valve. A filter 'i2 is mounted in the valve 66 so that fluid flowoccurring between opening 69 and ports 1| must pass through the filter.In the arrangement of the valves 61| and 55, the valve members 63 faceoutward or away from the chambers I6 and .Y

Thus fluid ilowing from the chambers must pass through the restrictedpassage represented by ports filter l2 and opening 69. Fluid owing inthe opposite direction, however, may unseat valve members 66 and passfreelytethe'chamber I6 or In the operation of the apparatus asa shimmydampener, the parts occup the positions shown in Fig. 1. Thus, the slidevalve 23 is in a neutral position with the flanges 24 and 25 thereonblocking the ports 29 and 3|. Thus even though fluid from the source edshould be admitted tothe bore i8 itis rdenied escape therefrom. Thevalve 6| is, however, set at this time to by-.pass the The slide valve`i8 .is in its extreme right .hand position, with radial vport 52registering with passage 42 and radial port offset from the passage i6which accordringly is closed. Passage 31 is, in this position of thevalve, open for communication with passage [al and bore 49.

Torque impulses applied to the 4shaft i3 are transmitted to the pistonassembly i2|3ili in the form of an axial thrust. yAssuming this thrustto occur .ina leftward direction, .the pressure in chamber i6 4risesforcing `fluid out .passage ci and past valve L64 by way of ports kiiand opening 69, the restriction 4to flow thus imposed effectivelyAdamping the movement of the .piston assembly. The chambers |6 `and |7|are in cornmunication with one .another -and with .the accumulator 38,passage I being connected throughgroove 33 with passage t2 which, as hasbeen seen, -is connected through .port 52 and bore i9 with passage 3lleading to accumulator 38 and with passage il Aleading to chamber il. Asfluid is forced out -of one chamber I6 or yby motion -of the pistonassembly, therefore, a like amount `of fluid is admitted to the otherchamber, the valve element-65 yielding for free Vflow of the make-upfluid.

In the operation of the apparatus vfor power steering, the valve 6| isset as shown in Fig. 2, to direct pressure uid from the pump 59 throughthe passage t3. Having access through branch passage l5 .to the end ofvalve 48, the pressure fluid moves valve 4 8 to a seat in the left handend of chamber 39 as shown in Fig. 2. As .so positioned, the port `5|communicates with .passage 43, bore 133 communicates with passage 4l andpassages 31 and A2 are closed.

The rotation of control input shaft i9 out of the position of Fig. 1 iseffective through slot 2| and pin 22 to `raise or lower theslide valve23. Assuming the input shaft to have been turned in -a direction to movethe pin 22 rightward in the slot 2 I, the slide valve 23 is lowered, asVseen in Fig. '2. As a result, the flanges 2li Yand .i cve out of theirneutral blocking positions and take up other positions wherein ports 23and Ec communicate with 'one another and ports 3c and 3| communicatewith one another. Thus the pressure fluid in passage 43 is admittedthrough groove 3i and ports 3|) to the chamber I8 and flows out of thechamber by way of ports 4 3| and groove 35 to passage 46. From passage46 the pressure fluid is directed through ports 5| and bore i3 in valvet8 to the passage il and is conducted thereby to the pressure chamberl1. The elevated pressure in chamber serves to move the piston assembly|2|3|| leftward whereupon shaft it is turned in the direction of .theleft hand directional arrow at lthe lower end of shaft I0. Such motionof the piston .assembly serves to displace fluid from the chamber |6,which fluid passes to the accumulator 33 vby way of passage 4|, groove33, ports 28, groove 32 and passage 33. The described turning motion kofthe output shaft lll is effective through -slot V2| and pin 22 to raisethe slide valve 23.

Wl'len, in response to such motion, the slide valve is restored to theYneutral position of Fig. 1, flow through the slide valve from passagei3 is interrupted and the pressure fluid actuation of shaft |63accordingly is discontinued. It will be understood that arreversedirection of rotation of the shaft i9 will have a reverse effect, thatis it will connect .the chamber I5 .to the pressure supply line 53 andwill Connect the chamber Il to the accumulator. In the Vlatter regard,it will be noted that if the slide valve 23 is raised from its Fig. 1position, the passage i6 opens into the bottom of bore I3 and socommunicates through bore 26, ports 2l, ports 28 and groove 32 withpassage 35 leading to the accumulator 33. It will further be understoodthat thecontrol input shaft i9 is operator or pilot controlled and canbe turned at any rate and in any degree that .may be required. Theoutput shaft le will duplicate such motion and will at the same timerestore the slide valve 23 to a neutral position so that lthe apparatusmay be conditioned for the next move'- ment of the control input shaft.

With regard to .pump 259 and valves t! and 63 it will `be understoodthat these elements are merely illustrative of one arrangement forsupplying fluid under pressure to the passage Y43. Other arrangementsare of course possible, the requirement being merely Athat pressure -besupplied the passage it for power steering Aand-be discontinued forshimmy dampening. In connection with the discontinuing of such pressuresupply, the passage i5 -'may be connected, Vas shown, by a `passage i3,incorporating a restriction 14, with the source vlil of hydraulicpressure. This passage will simplify .return of the slide valve 46 tothe position of .1 when the valve 6| is adjusted from its Fig. 2 'to itsFig. l position.

In power steering, wherein added fluid `is forced Vinto the accumulator,and on account of rising temperature, the pressure .in chamber Y38 tendsto rise. Such rise is kept toa lnia-X'iin-um value by the check valve 57which allows-excess fluid to return through passage :it to the inletside 1of pump 53.

What is claimed is:

1. Power steering apparatus, includ-ing a rotatable power output shaft,`a control input shaft arranged for Vrotary and axial motions, saidinput shaft being received in one lend `of said `output shaft,rpin-in-slot connection vbetween said input shaft and eut-.put lshaftresolving a relative rotary motion between said shafts 'inte an axialmotion of said input shaft, Aand a hydraulic servo-motor for rotatingsaid output shaft, said motor including va slide valve on the inner endof said input shaft.

2. In a combined shimmg,7 dampener and power steering apparatus, arotary power output shaft,-

a pinion on said shaft, a rack meshing with said pinion, pistons on theends of said racks, pressure chambers receiving said pistons, a pressureuid source and a reservoir, said chambers being filled with fluid fromsaid reservoir, restrictor valves inhibiting escape of fluid from saidchambers, a control input shaft in telescoping relation to said outputshaft and arranged for relative rotary and axial motions, a connectionbetween said shafts providing for axial motion of said input shaft inresponse to relative rotary motion of said shafts, a slide valveconstructed as an extension of said input shaft, passages extending fromsaid pressure chambers and connected by said slide valve alternativelyto said pressure fluid source and said reservoir, another valve toconnect said passages to said reservoir, said other valve being settableto an ineffective position wherein fluid flow is controlled by saidslide valve, and a pressure fluid connection from said source to setsaid other valve to ineffective position.

3. A combined power steering and shimmy dampening apparatus, including arotatable power output shaft, a control input shaft in telescopingrelation to said output shaft and ha' ing a pin-in-slot connectiontherewith resolving a relative rotary motion between said shafts into anaxial motion of said input shaft, a hydraulic fluid reservoir and asource of hydraulic fluid under pressure, a pressure fluid operatedpiston connected to said output shaft, a slide valve connected to saidinput shaft for effecting alternating connections between said pistonand said reservoir and said pressure fluid source, said slide valvehaving neutral position in which pressure fluid from said source isdenied access to either side of said piston, and a second slide valvesettable to a position. communicating said reservoir with both sides ofsaid piston.

4. A combined power steering and shimmy dampening apparatus, including apower output shaft, a piston assembly positively connected to said shaftalternatively to assume a driving and driven relationship thereto, aclosed hydraulic circuit receiving said piston assembly and damping themotion thereof transmitted by rotational impulses of said output shaft,said circuit having opposite sides as dened by said piston assembly,selectively operable means for admitting fluid pressure to said circuit,a slide Valve to control the application of such pressure to said pistonassembly to apply rotational force to said output shaft, a control inputshaft for adjusting said slide valve, a mechanical follow up connectionbetween said output shaft and said slide Valve for adjusting said slidevalve in correspondence with the movements of said output shaft, asecond slide valve in said circuit, and a reservoir communicatingthrough said second slide valve with the opposite sides of said circuit,said second slide Valve being operable by fluid admitted by saidselectively operable means to condition said circuit for power steeringunder the control of the first said slide valve.

WARREN H. CLARK.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,467,209 Sumner Sept. 4, 1923 1,894,098 Janisch Jan. 10, 19331,905,065 Scholl Apr. 25, 1933 2,227,375 Carlson Dec. 31, 1940 2,261,444Neubert, Jr. Nov. 4, 1941 2,350,229 Harrington May 30, '1944 "2368,135Hamill Jan. 30, 1945 2,418,325 Wassall et a1. Apr. 1, 1947

